The present invention is directed to the use of 2-guanidino-4-(2-methyl-4-imidazolyl)thiazole, 2-(N-pentyl-N'-guanidiano)-4-(2-methyl-4-imidazolyl)thiazole and analogs (or pharmaceutically acceptable salts thereof) in the treatment of rheumatoid arthritis. In spite of the wide use of steroidal and nonsteroidal antiinflammatory agents, rheumatoid arthritis remains an inadequately treated disease. For example, in many individuals, the gastrointestinal side effects associated with said antiinflammatory agents effectively prevents their use. Thus, present use of 2-guanidino-4-(2-methyl-4-imidazolyl)thiazole and its N-pentyl analog, lacking such gastrointestinal side effects, represents a valuable addition to the physician's aramentarium of agents for the treatment of rheumatoid arthritis.
2-Guanidino-4-(2-methyl-4-imidazolyl)thiazole, analogs, and pharmaceutically acceptable salts thereof have been previously reported as histamine-H.sub.2 antagonists, and so are useful as gastric acid antisecretory and antiulcer agents; LaMattina and Lipinski, U.S. Pat. No. 4,374,843 (1983). An improved method for the preparation of 2-guanidino-4-(2-methyl-4-imidazolyl)-thiazole and its salts, in particular the dihydrochloride preferred for use in the present invention, is also disclosed hereinafter in specific examples below.
2-(N-Pentyl-N'-guanidino)-4-(2-methyl-4-imidazolyl)-thiazole is the subject of copending U S. application of Reiter, Ser. No. 605,510, filed April 30, 1984, for "2-(N-Substituted guanidino)-4-heteroarylthiazole Antiulcer Agents." The method of preparing said N-pentylguanidino compound and employing same as an antiulcer and/or as a gastric antisecretory agent is also detailed hereinafter.